<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <title>Title</title>
</head>
<style>
  .active{
    color: red;
  }
  .line{
    font-size: 30px;
  }
</style>
<body>
<div id="app">
  <h2 :class="[active,line]">{{message}}</h2>
  <h2 :class="getClasses()">{{message}}</h2>
</div>
<script src="../vue.js"></script>
<script>
  const app = new Vue({
    el: '#app',
    data: {
      message: 'hello',
      active:'active',
      line:'line'
    },
    methods:{
      getClasses:function () {
        return [this.active,this.line]
      }
    }
  })
</script>
</body>
</html>
